﻿Shader "Custom/NormalMapTangentSpace"
{
  Properties
    {
        _Color("Color Tint",Color) = (1,1,1,1)
        _MainTex("Main Tex",2D) = "white"{}
        _BumpMap("Normal Map",2D) = "bump"{}
        _BumpScale("Bump Scale",Float) = 1.0
        _Specular("Specular",Color) = (1,1,1,1)
        _Gloss("Gloss",Range(8.0,256)) = 20
    }
        SubShader
        {
            Pass
            {
                Tags{"LightMode" = "ForwardBase"}
 
                CGPROGRAM
 
    #pragma vertex vert
    #pragma fragment frag
 
    #include "Lighting.cginc"
 
                fixed4 _Color;
                sampler2D _MainTex;
                float4 _MainTex_ST;
                sampler2D _BumpMap;
                float4 _BumpMap_ST;
                float _BumpScale;
                fixed4 _Specular;
                float _Gloss;
 
                struct a2v
                {
                    float4 vertex:POSITION;
                    float3 normal:NORMAL;
                    float4 tangent:TANGENT;
                    float4 texcoord : TEXCOORD0;
                };
 
                struct v2f
                {
                    float4 pos:SV_POSITION;
                    float4 uv:TEXCOORD0;
                    float3 lightDir:TEXCOORD1;
                    float3 viewDir:TEXCOORD2;
                };
 
                v2f vert(a2v v)
                {
                    v2f o;
 
                    o.pos = UnityObjectToClipPos(v.vertex);
 
                    o.uv.xy = v.texcoord.xy * _MainTex_ST.xy + _MainTex_ST.zw;
                    o.uv.zw = v.texcoord.xy * _BumpMap_ST.xy + _BumpMap_ST.zw;
 
                    float3 binormal = cross(normalize(v.normal), normalize(v.tangent.xyz)) * v.tangent.w;
                    float3x3 rotation = float3x3(v.tangent.xyz, binormal, v.normal);
 
                    //TANGENT_SPACE_ROTATION;
 
                    o.lightDir = mul(rotation, ObjSpaceLightDir(v.vertex)).xyz;
                    o.viewDir = mul(rotation, ObjSpaceViewDir(v.vertex)).xyz;
                    return o;
                }
 
                fixed4 frag(v2f i) :SV_Target
                {
                    fixed3 tangentLightDir = normalize(i.lightDir);
                    fixed3 tangentViewDir = normalize(i.viewDir);
                    fixed4 packedNormal = tex2D(_BumpMap, i.uv.zw);
                    fixed3 tangentNoraml;
 
                    tangentNoraml.xy = (packedNormal.xy * 2 - 1) * _BumpScale;
                    tangentNoraml.z = sqrt(1.0 - saturate(dot(tangentNoraml.xy, tangentNoraml.xy)));
 
                    //tangentNoraml = UnpackNormal(packedNormal);
                    //tangentNoraml.xy *= _BumpScale;
                    //tangentNoraml.z = sqrt(1.0 - saturate(dot(tangentNoraml.xy, tangentNoraml.xy)));
 
                    fixed3 albedo = tex2D(_MainTex, i.uv).rgb * _Color.rgb;
                    fixed3 ambient = UNITY_LIGHTMODEL_AMBIENT.xyz * albedo;
                    fixed3 diffuse = _LightColor0.rgb * albedo * max(0, dot(tangentNoraml, tangentLightDir));
                    fixed3 halfDir = normalize(tangentLightDir + tangentViewDir);
                    fixed3 specular = _LightColor0.rgb * _Specular.rgb * pow(max(0, dot(tangentNoraml, halfDir)), _Gloss);
                    return fixed4(ambient + diffuse + specular, 1.0);
                }
            ENDCG
        }
        }
            Fallback "Specualr"
}
